Areas of fog, some locally dense, are expected to develop across portions of Deep South Texas and the Rio Grande Valley overnight and into Thursday morning. Visibility may be reduced to less than 2 miles at times, with locally dense fog to one-quarter mile or less. A Dense Fog Advisory may be needed if dense fog becomes widespread. Use caution if traveling as visibility may change rapidly in a short amount of time. Use low beam headlights and leave extra distance between your vehicle and others on the road.